Watch video: How to choose the cleanest toilet, the mathematical way

Choosing the right public toilet is not easy, especially when you have hundreds of them and a lot of them not well-maintained. So how do you decide which toilet to use?

Dr Ria Symonds from the University of Nottingham in the video for YouTube channel Numberphile tells you the mathematical way of choosing the cleanest toilet.

“If you ever go to a music festival, especially a music festival in the UK, you might come across the problem that there’s always lots of toilets for you to choose from. The problem with these toilets is they’re not always that well looked after,” adds Dr Symonds.

“For example, while waiting in the queue, you go to the first toilet and open the door, and it’s really not that nice, you don’t want to use that toilet. You can try opening the next toilet. You find out that it’s marginally better, but still not that good. There are hundreds of such toilets and the problem is which one to use. You need not open each one of the toilets, there must be an optimum number we can look at,” the mathematician says in the video.

There are hundreds of such toilets and the problem is which one to use. Source: Youtube

She then goes on to take a hypothetical exmaple of a small music concert where there are just three toilets – one is disgusting, second is slightly better and the third is perfect.

“Ideally I’m looking for the best toilet, the most hygienic, the cleanest toilet, one with plenty of toilet paper in there and hand sanitiser and has been looked after,” she says.

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So what’s the solution.

Reject 37% Then take first one that is “best so far” (Watch video to know how she concluded the percentage)

“After that, you should then pick the next best toilet that you see as compared to the previous 37, which will get you the optimum standard of toilet,” says Dr Symonds.

So after the 37th toilet, you have a 37 per cent chance that a toilet you pick is actually the best category of toilet in the remaining toilets.